📦 chenrui333 / meetup-scala-class

Meetup Scala Class

Welcome to Meetup's Scala class!

This project will help make it easy to get started with Scala.

Using the REPL

You can launch an interactive REPL (a read evaluate print loop) by running the ./sbt console command in your terminal (such as Terminal.app on OSX). When you run this command you will see some output and a welcome message, such as:

[info] Loading global plugins from /Users/osheim/.sbt/0.13/plugins
[info] Set current project to meetup-scala-class (in build file:/Users/osheim/meetup-scala-class/)
[info] Starting scala interpreter...
[info]
Welcome to Scala version 2.10.4 (Java HotSpot(TM) 64-Bit Server VM, Java 1.7.0_45).
Type in expressions to have them evaluated.
Type :help for more information.

scala>

You can exit the REPL by typing :quit and if you type :help you can get a list of commands the REPL supports (but you won't need these right now).

The "scala>" prompt allows you to evaluate simple Scala expressions. For example, we can use Scala as a calculator:

scala> 1 + 1
res0: Int = 2

scala> 11 * 22 * 33
res1: Int = 7986

scala> math.sqrt(2385932.325)
res2: Double = 1544.6463430183624

The REPL is a great way to test out small snippets of Scala code, and this course will encourage you to try out new things as you discover them.

Once you are building larger expressions, or things you will want to repeatedly use, it can be nice to define them in files, rather than typing them in manually. The :load command allows you to load the contents of a file, exactly as if you typed in each line.

If you have a file called foo.repl that contains:

1 + 1
2 * 3
4 * 5 - 6

Then here is how you'd load it in the REPL:

scala> :load foo.repl
Loading foo...
res0: Int = 2
res1: Int = 6
res2: Int = 14

Using SBT

You can launch SBT (the Scala Build Tool) by running the ./sbt command. This tool is used by Scala programmers to compile, package, and run their programs.

There's a lot to learn about SBT but for now you will only need to use the following commands:

• console Launch the REPL. This is described in the previous section.

• compile Compile the project's source code (files ending in .scala).

• run Compile and run the project's source code.

Source code should be kept in src/main/scala although SBT will actually compile .scala files found anywhere in the project.

Lectures

• doc/class1.md